Smooth heuristic optimization on a complex chemical subspace

Elward, Jennifer M.; Rinderspacher, B. Christopher

doi:10.1039/c5cp02177d

Cited by 11 publications

(13 citation statements)

References 57 publications

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“…Convergence is reached when a single site modification does not result anymore in an improved property value. Even though there exist more recently introduced inverse design methods that may outperform the BFS method based on efficacy or larger CCS exploration ( Elward and Rinderspacher, 2015 ; Strasser et al, 2016 ; Häse et al, 2018 ), BFS has the key advantage of systematically delivering essential information on how the type and location of each possible substituent influences our property of interest, since in every global iteration all substituents are tested on all available sites ( Teunissen et al, 2017 ).…”

Section: Theoretical Background: Inverse Molecular Designmentioning

confidence: 99%

Fine-Tuning of Nonlinear Optical Contrasts of Hexaphyrin-Based Molecular Switches Using Inverse Design

et al. 2021

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In the search for new nonlinear optical (NLO) switching devices, expanded porphyrins have emerged as ideal candidates thanks to their tunable chemical and photophysical properties. Introducing meso-substituents to these macrocycles is a successful strategy to enhance the NLO contrasts. Despite its potential, the influence of meso-substitution on their structural and geometrical properties has been scarcely investigated. In this work, we pursue to grasp the underlying pivotal concepts for the fine-tuning of the NLO contrasts of hexaphyrin-based molecular switches, with a particular focus on the first hyperpolarizability related to the hyper-Rayleigh scattering (βHRS). Building further on these concepts, we also aim to develop a rational design protocol. Starting from the (un)substituted hexaphyrins with various π-conjugation topologies and redox states, structure-property relationships are established linking aromaticity, photophysical properties and βHRS responses. Ultimately, inverse molecular design using the best-first search algorithm is applied on the most favorable switches with the aim to further explore the combinatorial chemical compound space of meso-substituted hexaphyrins in search of high-contrast NLO switches. Two definitions of the figure-of-merit of the switch performance were used as target objectives in the optimization problem. Several meso-substitution patterns and their underlying characteristics are identified, uncovering molecular symmetry and the electronic nature of the substituents as the key players for fine-tuning the βHRS values and NLO contrasts of hexaphyrin-based switches.

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Section: Theoretical Background: Inverse Molecular Designmentioning

confidence: 99%

Fine-Tuning of Nonlinear Optical Contrasts of Hexaphyrin-Based Molecular Switches Using Inverse Design

et al. 2021

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“…In the following, we quickly recapitulate the working equations used for the HNNS , and introduce EGO for combinatorial optimization in CCS. We furthermore introduce and discuss the consequences of reordering in the context of optimization complexity on HNNS and EGO as well as their theoretical justifications.…”

Section: Background and Theorymentioning

confidence: 99%

“…Consequently, a number of methods have been developed to explore chemical subspaces efficiently. ,,,− Lack of structure may express itself in property roughness or constraint-induced feasibility islands. Prominent approaches to address these as well as search space discreteness are stochastic methods, ,,, in particular genetic algorithms (GAs). ,, GAs address the problem of property roughness by using populations of candidates of which not all members are solely evolved by performance.…”

Section: Introductionmentioning

confidence: 99%

Heuristic Global Optimization in Chemical Compound Space

Rinderspacher

2020

J. Phys. Chem. A

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We report developments in combinatorial optimization under constraints in chemical space. We considered random functions, which serve as a baseline to measure performance, and constrained optimizations over two databases of electrochromic molecules (∼5000 and 10 12 , respectively). These problems were optimized using sequential heuristic next-neighbor search (HNNS) (introduced in Elward and Rinderspacher Phys. Chem. Chem. Phys. 2015, 17, 24322 and Elward and Rinderspacher Mol. Syst. Des. Eng. 2018, 3, 485) and kernel-based efficient global optimization (EGO) with two reordering strategies. In addition to the average ordering method introduced with sequential HNNS, a new reordering based on a locally separable linear model is formulated and applied. Presented is the analysis of periodic kernels for EGO: the modified Dirichlet kernels D ̃n(x) = ∑ i n [cos(2πix) − (−1) i ]/i, the minimalist kernel K N (x) = cos(πx/N) 2 /2 − δ x /2, and an analogue to the popular Gaussian kernel, G N σ (x) = e −|x mod N| 2 /(2σ 2 ), where n is the order of the Dirichlet kernel, N is the number of choices on a combinatorial site, and σ is a broadening factor. We find that reordering is pivotal for high optimization efficiency, in both the average and worst-case scenarios. The new linear-estimation ordering paradigm is superior in the chemistry context. Furthermore, with judicious use of hyperparameters and algorithmic choices, EGO outperforms HNNS. The global optimum for the small chemical problem is found with >98% likelihood for all global search methods employing a linear reordering heuristic for organizing the search space.

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“…There were some systematic studies concentrating on researching the substitutions in the p-framework from theoretical and practical domains. [23][24][25][26][27] Jen's group introduced an alkylthiol group into the electron-bridge of the CLD-type chromophore, which achieved excellent photostability and large optical nonlinearity. Dalton's group synthesized a series of chromophores based on bis-(4-methoxyphenyl)hetero-aryl-amino type donors.…”

Section: Introductionmentioning

confidence: 99%

“…Introducing an additional amino group into the donor moiety could effectively modulate the conjugation of the p-electron networks and the electronic character of the charge transfer kinetics, which was proved by simulated calculations. 11,23,[27][28][29] As classical theories, Dewar's rules 30 have been widely applied into chromophore structure design for increasing nonlinear optical activity and stability. 31,32 On the basis of this theory, a donor-bridge-acceptor push-pull type nonlinear optical chromophore shows alternating electronegativities along the charge-transfer direction (Fig.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear optical chromophores based on Dewar's rules: enhancement of electro-optic activity by introducing heteroatoms into the donor or bridge

Yang

Liu

et al. 2015

Phys. Chem. Chem. Phys.

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In this work, we investigated the enhancement of the electro-optic response by introducing electron-rich heteroatoms as additional donors into the donor or bridge of a conventional second-order nonlinear optical chromophore. A series of chromophores C2-C4 based on the same tricyanofuran acceptor (TCF) but with different heteroatoms in the alkylamino phenyl donor (C2 or C3) or thiophene bridge (C4) have been synthesized and systematically investigated. Density functional theory calculations suggested that chromophores C2-C4 had a smaller energy gap and larger first-order hyperpolarizability (β) than traditional chromophore C1 due to the additional heteroatoms. Single crystal structure analyses and optimized configurations indicate that the rationally introduced heteroatom group would bring larger β and weaker intermolecular interactions which were beneficial for translating molecular β into macro-electro-optic activity in electric field poled films. The electro-optic coefficient of poled films containing 25 wt% of these new chromophores doped in amorphous poly-carbonate afforded values of 83 and 91 pm V(-1) at 1310 nm for chromophores C3 and C4, respectively, which are two times higher than that of the traditional chromophore C1 (39 pm V(-1)). High r33 values indicated that introducing heteroatoms to the donor and bridge of a conventional molecular structure can efficiently improve the electron-donating ability, which improves the β. The long-chain on the donor or bridge part, acting as the isolation group, may reduce inter-molecular electrostatic interactions, thus enhancing the macroscopic EO activity. These results, together with good solubility and compatibility with the polymer, show the new chromophore's potential application in electro-optic devices.

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Smooth heuristic optimization on a complex chemical subspace

Cited by 11 publications

References 57 publications

Fine-Tuning of Nonlinear Optical Contrasts of Hexaphyrin-Based Molecular Switches Using Inverse Design

Fine-Tuning of Nonlinear Optical Contrasts of Hexaphyrin-Based Molecular Switches Using Inverse Design

Heuristic Global Optimization in Chemical Compound Space

Nonlinear optical chromophores based on Dewar's rules: enhancement of electro-optic activity by introducing heteroatoms into the donor or bridge

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